Polymers and photoresist compositions comprising same

ABSTRACT

The invention includes polymers that contain a polymers of the invention contain one or more 1) carbonate units and/or 2) a lactone provided by a monomer having a ring oxygen adjacent to the monomer vinyl group. The invention also provides photoresists that contain such polymers, particularly for imaging at short wavelengths such as sub-200 nm.

The present application claims the benefit of U.S. provisionalapplication No. 60/271,402, filed Feb. 25, 2001, which is incorporatedherein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to new polymers that contain units offused carbonate groups and/or a lactone provided by a monomer having aring oxygen adjacent to the monomer vinyl group. Polymers of theinvention are highly useful as a resin component for photoresistcompositions, particularly chemically-amplified positive-acting resiststhat can be effectively imaged at short wavelengths such as sub-200 nm,particularly 193 nm.

2. Background

Photoresists are photosensitive films used for transfer of images to asubstrate. A coating layer of a photoresist is formed on a substrate andthe photoresist layer is then exposed through a photomask to a source ofactivating radiation. The photomask has areas that are opaque toactivating radiation and other areas that are transparent to activatingradiation. Exposure to activating radiation provides a photoinducedchemical transformation of the photoresist coating to thereby transferthe pattern of the photomask to the photoresist-coated substrate.Following exposure, the photoresist is developed to provide a reliefimage that permits selective processing of a substrate.

A photoresist can be either positive-acting or negative-acting. For mostnegative-acting photoresists, those coating layer portions that areexposed to activating radiation polymerize or crosslink in a reactionbetween a photoactive compound and polymerizable reagents of thephotoresist composition. Consequently, the exposed coating portions arerendered less soluble in a developer solution than unexposed portions.For a positive-acting photoresist, exposed portions are rendered moresoluble in a developer solution while areas not exposed remaincomparatively less developer soluble. Photoresist compositions aredescribed in Deforest, Photoresist Materials and Processes, McGraw HillBook Company, New York, ch. 2, 1975 and by Moreau, SemiconductorLithography, Principles, Practices and Materials, Plenum Press, NewYork, ch. 2 and 4.

More recently, chemically-amplified-type resists have been increasinglyemployed, particularly for formation of sub-micron images and other highperformance applications. Such photoresists may be negative-acting orpositive-acting and generally include many crosslinking events (in thecase of a negative-acting resist) or deprotection reactions (in the caseof a positive-acting resist) per unit of photogenerated acid. In thecase of positive chemically-amplified resists, certain cationicphotoinitiators have been used to induce cleavage of certain “blocking”groups pendant from a photoresist binder, or cleavage of certain groupsthat comprise a photoresist binder backbone. See, for example, U.S. Pat.Nos. 5,075,199; 4,968,581; 4,883,740; 4,810,613; and 4,491,628, LA andCanadian Patent Application 2,001,384. Upon cleavage of the blockinggroup through exposure of a coating layer of such a resist, a polarfunctional group is formed, e.g., carboxyl or imide, which results indifferent solubility characteristics in exposed and unexposed areas ofthe resist coating layer. See also R. D. Allen et al., Proceedings ofSPIE, 2724:334-343 (1996); and P. Trefonas et al. Proceedings of the11th International Conference on Photopolymers (Soc. Of PlasticsEngineers), pp 44-58 (Oct. 6, 1997).

While currently available photoresists are suitable for manyapplications, current resists also can exhibit significant shortcomings,particularly in high performance applications such as formation ofhighly resolved sub-half micron and sub-quarter micron features.

Consequently, interest has increased in photoresists that can bephotoimaged with short wavelength radiation, including exposureradiation of about 250 nm or less, or even about 200 nm or less, such aswavelengths of about 248 nm (provided by KrF laser) or 193 nm (providedby an ArF exposure tool). See European Published Application EP915382A2.Use of such short exposure wavelengths can enable formation of smallerfeatures. Accordingly, a photoresist that yields well-resolved imagesupon 248 nm or 193 nm exposure could enable formation of extremely small(e.g. sub-0.25 μm) features that respond to constant industry demandsfor smaller dimension circuit patterns, e.g. to provide greater circuitdensity and enhanced device performance.

However, many current photoresists are generally designed for imaging atrelatively higher wavelengths, such as G-line (436 nm) and I-line (365nm) are generally unsuitable for imaging at short wavelengths such assub-200 nm. Even shorter wavelength resists, such as those effective at248 nm exposures, also are generally unsuitable for sub-200 nmexposures, such as 193 nm imaging.

More specifically, current photoresists can be highly opaque toextremely short exposure wavelengths such as 193 nm, thereby resultingin poorly resolved images.

It thus would be desirable to have new photoresist compositions,particularly resist compositions that can be imaged at short wavelengthssuch as sub-200 nm exposure wavelengths, particularly 193 nm.

SUMMARY OF INVENTION

We have now found novel polymers and photoresist compositions thatcomprise the polymers as a resin binder component. The photoresistcompositions of the invention can provide highly resolved relief imagesupon exposure to extremely short wavelengths, particularly sub-200 nmwavelengths such as 193 nm.

Polymers of the invention contain one or more 1) carbonate units (suchas provided by reaction of a vinyl carbonate e.g. vinylene carbonate)and/or 2) a lactone provided by a monomer having a ring oxygen adjacentto the monomer vinyl group such as α-angelicalactone andy-methylene-y-butyrolactone.

Polymers of the invention also may contain an oxygen- and/orsulfur/containing heteroalicyclic ring that is preferably fused to thepolymer backbone (i.e. at least two heteroalicyclic ring atoms as partof the polymer backbone). The heteroalicyclic ring has one or moreoxygen and/or sulfur atoms as ring members.

Preferred polymers of the invention also may contain a carbon alicyclicgroup (i.e. the group has all carbon ring members) that is fused to thepolymer backbone, i.e. the carbon alicyclic ring has at least two carbonring members that comprise the polymer backbone. Preferred fused carbonalicyclic groups are provided by polymerization of cyclic olefin(endocyclic double bond) compounds such as optionally substitutednorbornene groups.

Preferred heteroalicyclic polymer units may be substituted, e.g. byheteroalkyl groups such as ethers (alkoxy) preferably having 1 to about10 carbon atoms, alkylthio preferably having 1 to about 10 carbon atoms,alkylsulfinyl preferably 1 to about 10 carbon atoms, alkylsulfonylpreferably having 1 to about 10 carbon atoms, and the like. It has beensurprising found that such substituents can provide enhancedlithographic results, particularly enhanced substrate adhesion.

For use in photoresist compositions, polymers of the invention also willcontain one or more units that comprise photoacid-labile moieties. Thephotoacid-labile group may be a substituent of one or more of theabove-mentioned units, such as a substituent of a polymerized vinylalicyclic ether, vinyl alicyclic thioether or carbon alicyclic group.The photoacid labile moiety also may be present as an additional polymerunit, e.g. as a polymerized alkyl acrylate or alkylmethacrylate,particularly an acrylate having an alicyclic moiety such asmethyladamantyl acrylate or methyladamantyl methacrylate. Preferredalicyclic photoacid-labile moieties are tertiary ester alicyclichydrocarbon groups that have two or more fused or bridged rings.Preferred tertiary ester groups include optionally substitutedadamantyl, particularly methyl adamantyl as mentioned above; optionallysubstituted fencyl groups, particularly ethyl fencyl; optionallysubstituted pinanyl; and optionally substituted tricyclo decanylparticularly an alkyl-substituted tricyclo decanyl such as8-ethyl-8-tricyclodecanyl e.g. as provided by polymerization of8-ethyl-8-tricyclodecanyl acrylate and 8-ethyl-8-tricyclodecanylmethacrylate. Additional alicyclic ester groups also will be suitable,including additional bicyclic, tricyclic and other polycyclic moieties.

Polymers of the invention also may contain units in addition to theabove groups. For example, polymers of the invention also may containnitrile units such as provided by polymerization of methacrylonitrileand acrylonitrile. Additional contrast enhancing groups also may bepresent in polymers of the invention, such as groups provided bypolymermization of methacrylic acid, acrylic acid, and such acidsprotected as photoacid labile esters, e.g. as provided by reaction ofethoxyethyl methacrylate, t-butoxy methacrylate, t-butylmethacrylate andthe like.

Generally preferred polymers of the invention contain 3, 4 or 5 distinctrepeat units, i.e. preferred are terpolymers, tetrapolymers andpentapolymers that contain one or more heteroalicyclic groups asdisclosed herein.

Particularly preferred polymers of the invention include:

-   -   1) a polymer that contains distinct repeat units of i) a        carbonate and/or lactone as discussed above; ii) maleic        anhydride; and iii) an acrylate or methacrylate including those        that contain a photoacid-labile group such as t-butylacrylate,        adamantylacrylate and the like;    -   2) a polymer that contains distinct repeat units of i) a        carbonate and/or lactone as discussed above; ii) maleic        anhydride; and iii) a vinyl alicyclic, including carbon        alicyclics and heteroalicyclics as discussed above;    -   3) a polymer that contains distinct repeat units of i) a        carbonate and/or lactone as discussed above; ii) maelic        anhydride; and iii) a vinyl alicyclic, including carbon        alicyclics and heteroalicyclics as discussed above; and    -   4) a polymer that contains distinct repeat units of i) a        carbonate and/or lactone as discussed above; ii) maleic        anhydride; iii) a vinyl alicyclic, including carbon alicyclics        and heteroalicyclics as discussed above; and iv) an acrylate or        methacrylate including those that contain a photoacid-labile        group such as t-butylacrylate, adamantylacrylate and the like.

Polymers of the invention are preferably employed in photoresists imagedat 193 nm, and thus preferably will be substantially free of any phenylor other aromatic groups. For example, preferred polymers contain lessthan about 5 mole percent aromatic groups, more preferably less thanabout 1 or 2 mole percent aromatic groups, more preferably less thanabout 0.1, 0.02, 0.04 and 0.08 mole percent aromatic groups and stillmore preferably less than about 0.01 mole percent aromatic groups.Particularly preferred polymers are completely free of aromatic groups.Aromatic groups can be highly absorbing of sub-200 nm radiation and thusare undesirable for polymers used in photoresists imaged with such shortwavelength radiation.

Polymers of the invention also may be suitably employed in resists usedfor imaging at other wavelengths such as sub-300 nm and sub-170 mm,particularly 2248 nm and 157 nm. Polymers employed in resists imaged at248 nm suitably may contain aromatic groups, including phenyl groupsparticularly phenolic gropups as may be provided by reaction of thecorresponding vinyl monomer (e.g. vinylphenol). Polymers employed inresists imaged at 157 nm suitably have halogen substitution,particularly fluorine substitution such as may be provided byco-polymerization of a fluoro-olefin, e.g. tetrafluoroethylene.

The invention also provides methods for forming relief images, includingmethods for forming a highly resolved relief image such as a pattern oflines where each line has essentially vertical sidewalls and a linewidth of about 0.40 microns or less, and even a width of about 0.25,0.20 or 0.16 microns or less. The invention further provides articles ofmanufacture comprising substrates such as a microelectronic wafersubstrate or liquid crystal display or other flat panel displaysubstrate having coated thereon a polymer, photoresist or resist reliefimage of the invention. Other aspects of the invention are disclosedinfra.

DETAILED DESCRIPTION OF THE INVENTION

As discussed above, polymers of the invention contain one or more 1)carbonate units and/or 2) a lactone provided by a monomer having a ringoxygen adjacent to the monomer vinyl group.

Exemplary monomers that may be employed to provide such monomers includethe following:

As also discussed above, polymers of the invention may contain otherunits. Preferred polymers of the invention may contain additional (i.e.distinct from the carbonate and/or lactone) heteroalicyclic rings thatare preferably fused to a polymer backbone. The fused heterocyclic ringunits contain one or more oxygen and/or sulfur atoms. By stating hereinthat a cyclic group is fused to a polymer backbone, it is meant that tworing members of the cyclic group, typically two adjacent carbon atoms ofthe cyclic group, are also part of the polymer backbone. Such a fusedring can be provided by polymerizing a cyclic monomer that has anendocyclic double bond.

Additional preferred polymer units are polymerized carbon alicycliccompounds such as optionally substituted norbornene. As referred toherein, the term “carbon alicyclic group” means each ring member of thenon-aromatic group is carbon. The carbon alicyclic group can have one ormore endocyclic carbon-carbon double bonds, provided the ring is notaromatic.

Preferred polymers of the invention will contain at least about 2 to 5mole percent of fused heteroalicyclic units based on total units of thepolymer; more preferably from about 5 to 50 mole percent of fusedheteroalicyclic units based on total units of the polymer, still morepreferably from about 5 or 10 to about 40 or 50 percent of fusedheteroalicyclic units based on total units of the polymer.

Preferred polymers of the invention will contain at least about 2 to 5mole percent of carbon alicyclic units based on total units of thepolymer, more preferably from about 5 to 50 mole percent of fused carbonalicyclic units based on total units of the polymer; still morepreferably from about 5 or 10 to about 25 or 30 percent of fused carbonalicyclic units based on total units of the polymer.

In polymers of the invention that contain only heteroalicyclic units andcarbon alicyclic units, preferably the heterocyclic units will bepresent in an amount of from about 5 to about 90 or 95 mole percentbased on total polymer units, and the carbon alicyclic units will bepresent in an amount of from about 5 to about 90 or 95 mole percentbased on total polymer units.

In polymers of the invention that consist of heteroalicyclic units,carbon alicyclic units and maleic anhydride units (i.e. carbonate orlactone:carbon alicyclic:maleic anhydride terpolymers), preferably thecarbonate and/or lactone units will be present in an amount of fromabout 5 to about 10, 20, 30, 40, 50, 60, 70 or 80 mole percent based ontotal polymer units, the carbon alicyclic units (such as optionallysubstituted norbornene) will be present in an amount of from about 5 toabout 10, 20, 30, 40, 50, 60, 70 or 80 mole percent based on totalpolymer units, and the maleic anhydride units will be present from about5 to about 20, 30, 40 or 50 mole percent based on total polymer units;and more preferably the carbonate and/or lactone units will be presentin an amount of from about 5 to about 10, 20, 30, 40, 50 or 60 molepercent based on total polymer units, the carbon alicyclic units will bepresent in an amount of from about 5 to about 10, 20, 30, 40, 50 or 60mole percent based on total polymer units, and the maleic anhydrideunits will be present from about 5 to about 10, 15, 20, 25, 30, 40, or50 mole percent based on total polymer units. In such terpolymers,suitably the carbon alicyclic units will contain a photoacid labilesubstituents such as a photoacid-labile ester substituent.

In any event, polymers of the invention preferably comprise contain oneor more repeat units that comprise a photoacid-labile group. Thephotoacid-labile may be suitably a substituent of a carbon alicyclicring member (norbornene) or, alternatively and generally preferred, thephotoacid-labile moiety will be a polymer repeat unit distinct fromrepeat units containing an alicyclic group and may be e.g. a polymerizedacrylate or methacrylate group.

Preferred photoacid-labile groups are ester groups, particularly estersthat contain a tertiary alicyclic hydrocarbon ester moiety. Preferredtertiary alicyclic hydrocarbon ester moieties are polycyclic groups suchadamantyl, ethylfencyl or a tricyclo decanyl moiety. References hereinto a “tertiary alicyclic ester group” or other similar term indicatethat a tertiary alicyclic ring carbon is covalently linked to the esteroxygen, i.e. —C(═O)O—TR′where T is a tertiary ring carbon of alicyclicgroup R′. In at least many cases, preferably a tertiary ring carbon ofthe alicyclic moiety will be covalently linked to the ester oxygen, suchas exemplified by the below-depicted specifically preferred polymers.However, the tertiary carbon linked to the ester oxygen also can beexocyclic to the alicyclic ring, typically where the alicyclic ring isone of the substituents of the exocyclic tertiary carbon. Typically, thetertiary carbon linked to the ester oxygen will be substituted by thealicyclic ring itself, and/or one, two or three alkyl groups having 1 toabout 12 carbons, more typically 1 to about 8 carbons, even moretypically 1, 2, 3 or 4 carbons. The alicyclic group also preferably willnot contain aromatic substitution. The alicyclic groups may be suitablymonocyclic, or polycyclic, particularly bicyclic or tricyclic groups.

Preferred alicyclic moieties (e.g. group TR′ of —C(═O)O-TR′) ofphotoacid labile ester groups of polymers of the invention have ratherlarge volume. It has been found that such bulky alicyclic groups canprovide enhanced resolution when used in copolymers of the invention.

More particularly, preferred alicyclic groups of photoacid labile estergroups will have a molecular volume of at least about 125 or about 130Å³, more preferably a molecular volume of at least about 135, 140, 150,155, 160, 165, 170, 175, 180, 185, 190, 195, or 200 Å³. Alicyclic groupslarger than about 220 or 250 Å³ may be less preferred, in at least someapplications. References herein to molecular volumes designatevolumetric size as determined by standard computer modeling, whichprovides opted chemical bond lengths and angles. A preferred computerprogram for determining molecular volume as referred to herein isAlchemy 2000, available from Tripos. For a further discussion ofcomputer-based determination of molecular size, see T Omote et al,Polymers for Advanced Technologies, volume 4, pp. 277-287:

Particularly preferred tertiary alicyclic groups of photoacid-labileunits include the following, where the wavy line depicts a bond to thecarboxyl oxygen of the ester group, and R is suitably optionallysubstituted allyl, particularly C₁₋₈alkyl such as methyl, ethyl, etc.

Polymers of the invention also may contain photoacid-labile groups thatdo not contain an alicyclic moiety. For example, polymers of theinvention may contain photoacid-labile ester units, such as aphotoacid-labile alkyl ester. Generally, the carboxyl oxygen (i.e. thecarboxyl oxygen as underlined as follows: —C(═O)O) of thephotoacid-labile ester will be covalently linked to the quaternarycarbon. Branched photoacid-labile esters are generally preferred such ast-butyl and —(CH₃)₂CH(CH₃)₂.

Polymers of the invention also may contain additional units such ascyano units, lactone units or anhydride units. For example,acrylonitrile or methacrylonitrile may be polymerized to provide pendantcyano groups, or maleic anhydride may be polymerized to provide a fusedanhydride unit.

As discussed above, polymers of the invention are preferably employed inphotoresists imaged at short wavelengths, particularly sub-200 nm suchas 193 nm and 157 nm. Polymers also can be employed in photoresistsimaged at higher wavelengths such as 248 nm. For such higher wavelengthapplications, the polymer may suitably contain aromatic units, e.g.polymerized styrene or hydrostyrene units.

Polymers of the invention can be prepared by a variety of methods. Onesuitable method is an addition reaction which may include free radicalpolymerization, e.g., by reaction of selected monomers to provide thevarious units as discussed above in the presence of a radical initiatorunder an inert atmosphere (e.g., N₂ or argon) and at elevatedtemperatures such as about 70° C. or greater, although reactiontemperatures may vary depending on the reactivity of the particularreagents employed and the boiling point of the reaction solvent (if asolvent is employed). Suitable reaction solvents include e.g.tetrahydrofuran, ethyl lactate and the like. Suitable reactiontemperatures for any particular system can be readily determinedempirically by those skilled in the art based on the present disclosure.A variety of free radical initiators may be employed. For example, azocompounds may be employed such as azo-bis-2,4-dimethylpentanenitrile.Peroxides, peresters, peracids and persulfates also could be employed.

Other monomers that can be reacted to provide a polymer of the inventioncan be identified by those skilled in the art. For example, to providephotoacid-labile units, suitable monomers include e.g. methacrylate oracrylate that contains the appropriate group substitution (e.g. tertiaryalicyclic, t-butyl, etc.) on the carboxy oxygen of the ester group.Maleic anhydride is a preferred reagent to provide fused anhydridepolymer units. Itaconic anhydride also is a preferred reagent to provideanhydride polymer units, preferably where the itaconic anhydride haspurified such as by extraction with chloroform prior to polymerizationVinyl lactones are also preferred reagents, such as alpha-butyrolactone.

Some suitable vinyl (endocyclic double bond) heterocyclic monomers thatcan be polymerized to provide polymers of the invention include thefollowing:

Preferably a polymer of the invention will have a weight averagemolecular weight (Mw) of about 800 or 1,000 to about 100,000, morepreferably about 2,000 to about 30,000, still more preferably from about2,000 to 15,000 or 20,000, with a molecular weight distribution (Mw/Mn)of about 3 or less, more preferably a molecular weight distribution ofabout 2 or less. Molecular weights (either Mw or Mn) of the polymers ofthe invention are suitably determined by gel permeation chromatography.

Polymers of the invention used in photoresist formulations shouldcontain a sufficient amount of photogenerated acid labile ester groupsto enable formation of resist relief images as desired. For instance,suitable amount of such acid labile ester groups will be at least 1 molepercent of total units of the polymer, more preferably about 2 to 50mole percent, still more typically about 3 to 30 or 40 mole percent oftotal polymer units. See the examples which follow for exemplarypreferred polymers.

As discussed above, the polymers of the invention are highly useful as aresin binder component in photoresist compositions, particularlychemically-amplified positive resists. Photoresists of the invention ingeneral comprise a photoactive component and a resin binder componentthat comprises a polymer as described above.

The resin binder component should be used in an amount sufficient torender a coating layer of the resist developable with an aqueousalkaline developer.

The resist compositions of the invention also comprise a photoacidgenerator (i.e. “PAG”) that is suitably employed in an amount sufficientto generate a latent image in a coating layer of the resist uponexposure to activating radiation. Preferred PAGs for imaging at 193 nmand 248 nm imaging include imidosulfonates such as compounds of thefollowing formula:

wherein R is camphor, adamantane, alkyl (e.g. C₁₋₁₂ alkyl) andperfluoroalkyl such as perfluoro(C₁₋₁₂alkyl), particularlyperfluorooctanesulfonate, perfluorononanesulfonate and the like. Aspecifically preferred PAG isN-[(perfluorooctanesulfonyl)oxy]-5-norbornene-2,3-dicarboximide.

Sulfonate compounds are also suitable PAGs, particularly sulfonatesalts. Two suitable agents for 193 nm and 248 nm imaging are thefollowing PAGS 1 and 2:

Such sulfonate compounds can be prepared as disclosed in European PatentApplication 96118111.2 (publication number 0783136), which details thesynthesis of above PAG 1.

Also suitable are the above two iodonium compounds complexed with anionsother than the above-depicted camphorsulfonate groups. In particular,preferred anions include those of the formula RSO₃— where R isadamantane, alkyl (e.g. C₁₋₁₂ alkyl) and perfluoroalkyl such asperfluoro (C₁₋₁₂alkyl), particularly perfluorooctanesulfonate,perfluorobutanesulfonate and the like.

Other known PAGS also may be employed in the resists of the invention.Particularly for 193 nm imaging, generally preferred are PAGS that donot contain aromatic groups, such as the above-mentionedimidosulfonates, in order to provide enhanced transparency.

A preferred optional additive of resists of the invention is an addedbase, particularly tetrabutylammonium hydroxide (TBAH), ortetrabutylammonium lactate, which can enhance resolution of a developedresist relief image. For resists imaged at 193 nm, a preferred addedbase is a hindered amine such as diazabicyclo undecene ordiazabicyclononene. The added base is suitably used in relatively smallamounts, e.g. about 0.03 to 5 percent by weight relative to the totalsolids.

Photoresists of the invention also may contain other optional materials.For example, other optional additives include anti-striation agents,plasticizers, speed enhancers, etc. Such optional additives typicallywill be present in minor concentrations in a photoresist compositionexcept for fillers and dyes which may be present in relatively largeconcentrations, e.g., in amounts of from about 5 to 30 percent by weightof the total weight of a resist's dry components.

The resists of the invention can be readily prepared by those skilled inthe art. For example, a photoresist composition of the invention can beprepared by dissolving the components of the photoresist in a suitablesolvent such as, for example, ethyl lactate, ethylene glycol monomethylether, ethylene glycol monomethyl ether acetate, propylene glycolmonomethyl ether, prop ylene glycol monomethyl ether acetate and3-ethoxyethyl propionate. Typically, the solids content of thecomposition varies between about 5 and 35 percent by weight of the totalweight of the photoresist composition. The resin binder and photoactivecomponents should be present in amounts sufficient to provide a filmcoating layer and formation of good quality latent and relief images.See the examples which follow for exemplary preferred amounts of resistcomponents.

The compositions of the invention are used in accordance with generallyknown procedures. The liquid coating compositions of the invention areapplied to a substrate such as by spinning, dipping, roller coating orother conventional coating technique. When spin coating, the solidscontent of the coating solution can be adjusted to provide a desiredfilm thickness based upon the specific spinning equipment utilized, theviscosity of the solution, the speed of the spinner and the amount oftime allowed for spinning.

The resist compositions of the invention are suitably applied tosubstrates conventionally used in processes involving coating withphotoresists. For example, the composition may be applied over siliconwafers or silicon wafers coated with silicon dioxide for the productionof microprocessors and other integrated circuit components.Aluminum-aluminum oxide, gallium arsenide, ceramic, quartz, copper,glass substrates and the like are also suitably employed.

Following coating of the photoresist onto a surface, it is dried byheating to remove the solvent until preferably the photoresist coatingis tack free. Thereafter, it is imaged through a mask in conventionalmanner. The exposure is sufficient to effectively activate thephotoactive component of the photoresist system to produce a patternedimage in the resist coating layer and, more specifically, the exposureenergy typically ranges from about 1 to 100 mJ/cm², dependent upon theexposure tool and the components of the photoresist composition.

As discussed above, coating layers of the resist compositions of theinvention are preferably photoactivated by a short exposure wavelength,particularly a sub-300 and sub-200 nm exposure wavelength. As discussedabove, 193 nm is a particularly preferred exposure wavelength. 157 nmalso is a preferred exposure wavelength. However, the resistcompositions of the invention also may be suitably imaged at higherwavelengths. For example, a resin of the invention can be formulatedwith an appropriate PAG and sensitizer if needed and imaged at higherwavelengths e.g. 248 nm or 365 nm.

Following exposure, the film layer of the composition is preferablybaked at temperatures ranging from about 70° C. to about 160° C.Thereafter, the film is developed The exposed resist film is renderedpositive working by employing a polar developer, preferably an aqueousbased developer such as quaternary ammonium hydroxide solutions such asa tetra-alkyl ammonium hydroxide solution; various amine solutionspreferably a 0.26 N tetramethylammonium hydroxide, such as ethyl amine,n-propyl amine, diethyl amine, di-n-propyl amine, triethyl amine, ormethyldiethyl amine; alcohol amines such as diethanol amine ortriethanol amine; cyclic amines such as pyrrole, pyridine, etc. Ingeneral, development is in accordance with procedures recognized in theart.

Following development of the photoresist coating over the substrate, thedeveloped substrate may be selectively processed on those areas bared ofresist, for example by chemically etching or plating substrate areasbared of resist in accordance with procedures known in the art. For themanufacture of microelectronic substrates, e.g., the manufacture ofsilicon dioxide wafers, suitable etchants include a gas etchant, e.g. ahalogen plasma etchant such as a chlorine or fluorine-based etchant sucha Cl₂ or CF₄/CHF₃ etchant applied as a plasma stream. After suchprocessing, resist may be removed from the processed substrate usingknown stripping procedures.

All documents mentioned herein are incorporated herein by reference. Thefollowing non-limiting examples are illustrative of the invention

Example 1 Synthesis of Polymer Containing Vinylene Carbonate

Polymer of the above structure (units in the following molar amount asappearing from left to right: 20/10/30/40) was synthesized as follows.

A mixture of 2-methyladamantanyl methacrylate (15.64 g), maleicanhydride (4.91 g), norbornene (1.57 g), vinylene carbonate (2.87 g),and dimethyl-2,2′-azodiisobutyrate (0.77 g, 2 mol % of total monomers)in 25 g of dioxane was placed in a round-bottomed flask fitted with areflux condenser and nitrogen purge. The flask was then placed in apre-heated 85° C. oil bath. This reaction mixture was stirred at thistemperature for 24 hours, under nitrogen. After cooling the reactionmixture to room temperature, the solution was diluted to 33% (wt/wt)with dioxane. The polymer was isolated by precipitation into 1 L ofisopropyl alcohol, then filtered off and washed with an additional 100ml of isopropyl alcohol. Finally, the polymer was dried in a vacuum ovenat 40° C. for overnight, yield=60%.

Example 2 Synthesis of polymer Containing 4,7-Dihydro-1,3 dioxepin

A polymer of the above structure (units in the following molar amount asappearing from left to right: 20/10/30/40) was synthesized as follows.

A mixture of 2-methyladamantanyl methacrylate (15.35 g), maleicanhydride (4.82 g), norbornene (1.54 g), 4,7-dihydro-1,3 dioxepin (3.28g), and dimethyl-2,2′-azodiisobutyrate (0.76 g, 2 mol % of totalmonomers) in 25 g of dioxane was placed in a round-bottomed flask fittedwith a reflux condenser and nitrogen purge. The flask was then placed ina pre-heated 85° C. oil bath. This reaction mixture was stirred at thistemperature for 24 hours, under nitrogen. After cooling the reactionmixture to room temperature, the solution was diluted to 33% (wt/wt)with dioxane. The polymer was isolated by precipitation into 1 L ofisopropyl alcohol then filtered off and washed with an additional 100 mlof isopropyl alcohol. Finally, the polymer was dried in a vacuum oven at40° C. for overnight, yield=62%.

Example 3 Photoresist Preparation and Lithographic Processing

A photoresist of the invention is prepared by mixing the followingcomponents with amount expressed as weight percents based on totalweight of the resist

Resist components Amount (wt. % based on total solids) Resin binder 28.2Photoacid generator 0.52 Basic additive 0.03 Surfactant 0.03

The resin binder is the polymer of Example 2 above. The photoacidgenerator is triphenylsulfonium triflate. The basic additive istriisopropanol amine. The surfactant is Silwet (Dow Chemical). Thoseresist components were formulated at 16 wt % solids in a solvent of2-heptatone.

The formulated resist composition is spin coated onto HMDS vapor primed4 inch silicon wafers and softbaked via a vacuum hotplate at 130° C. for60 seconds. The resist coating layer is exposed through a photomask at193 nm using an ISI microstepper, and then the exposed coating layersare post-exposure baked (PEB) at about 130° C. The coated wafers arethen treated with alkaline aqueous developer (0.26N aqueoustetramethylammonium hydroxide solution to develop the imaged resistlayer and provide a relief image.

Examples 4-7 Syntheses of Monomers Useful in Preparation of Polymers ofthe Invention Example 4 EtTCD Methacrylate monomer synthesis

8-ethyl-8-tricyclodecanylmethacrylate (EtTCD methacrylate) was preparedas following using the reagents and amounts thereof as specified in thefollowing table.

Material Amt (g) Amt (ml) Moles Source TCD 150.22 ′1.00 TCIEthylmagnesiumchloride (25%) 390.85 ˜379.5 ˜1.10 ACROS Methacryloylchloride 120.22 ˜112.4 ˜1.15 Aldrich Tetrahydrofuran 480 540 Aldrich

All reaction glassware was dried in the oven overnight at 100° C. Theglassware was set up and cooled under a stream of nitrogen. The reactionwas carried out under a blanket of nitrogen.

To a 2 L 3N-RB flask fitted with a gas inlet, thermometer, overheadstirrer and a rubber septum was added 400 g of ethylmagnesium chloride,25 wt % solution in tetrahydrofuran (clear, amber solution) via a doubletipped needle using nitrogen pressure. The mixture was cooled to −25 to−30° C. using a dry ice/isopropanol bath. While the ethylmagnesiumchloride solution was cooling the 153.6 g of tricyclodecane (TCD) wasdissolved in 480 g of tetrahydrofuran. To a 1 L 3N-RB flask equippedwith a gas inlet, glass stopper and a rubber septum was added the 153.6g of TCD. The anhydrous, inhibitor free tetrahydrofuran was transferredto the 1 L flask via a double tipped needle using nitrogen pressure.When the ethylmagnesium chloride was at −25 to −30° C., the TCD/THFsolution was transferred over a 2 hr period to the 2 L 3N-RB flaskcontaining the ethylmagnesium chloride via a double tipped needle usingnitrogen pressure. The cooling bath was removed and the reaction mixturewas stirred for 2 hr. After stirring for 2 hr the mixture was againcooled to −25 to −30° C. using a dry ice/isopropanol bath. Themethacryloyl chloride (120.22 g) was then added dropwise over a 1 hourperiod using a 125 ml pressure equalizing dropping funnel. The reactionwas allowed to come to room temperature with overnight stirring. A whiteprecipitate developed from the clear amber colored reaction solutionWater (DI) was added until all of the salts had dissolved (˜500 ml) andtwo distinct layer were seen. The layers were separated and the organic(upper) layer was washed with 2×400 ml DI water then dried overmagnesium sulfate. The THF was removed leaving 258 g of an orange oil.The orange oil was dissolved in 400 g of hexane then passed through a400 g silica gel plug which had been preconditioned with hexane. Thesilica was washed with hexane until all of the product was removed (spotfiltrate on a TLC plate and illuminate under short UV). The hexane wasremoved leaving 202.8 g of an clear, colorless oil. Theoretical yield:248.4 g; yield: 81.6%

Example 5 Synthesis of Norbornene Valerolactone

A solution of valerolactone (50.1 g) in 150 mL of anhydrous THF wasplaced in a three-neck-bottomed flask at −78° C. (Dry Ice/acetone). Toit, solution of LDA (250 in L, 2M) in 250 mL anhydrous THF was addeddropwise. The reaction mixture was stirred at this temperature for 4hours. Then, the thermal cracking of paraformaldehyde (36.94 g, excess)was bubbled into the reaction mixture. After the paraformaldehyde wasall cracked, the reaction mixture was stirred at the same bath andstirred for overnight. Then, the solvent was removed by rotary pump andthe residue was added 500 mL CH₂Cl₂ and washed with NaHCO₃ (aq, sat.)and water several times (3×500 mL). The combination organic solvent wasdried over MgSO₄ and the solvent was removed by rotary pump. The desiredproduct was distilled under vacuum (135-140° C./8 mmHg)

The methylene-valerolactone was dissolved in dichloromethane and freshlycracked cyclopentadiene was added. The reaction mixture was stirred atroom temperature for 3 hours, then heated to 40° C., and held at 40° C.overnight. The reaction mixture was then slowly cooled to roomtemperature. The methylene chloride was removed under reduced pressure,leaving an oil. The crude oil was then distilled under reduced pressureto afford pure product.

Example 6 Synthesis of 8-methyltricyclodecanyl methacrylate

A solution of 125 ml of 1.4 M methyl lithium (in ethyl ether) in 100 mlof hexane was decanted into a three neck round-bottom flask at anice-water bath. To it, a solution of 24.00 g oftricyclo[5.2.1.0]decan-8-one in hexane was added dropwise. Afteraddition, the reaction mixture was stirred for 4 hours at 0° C. Then, asolution of 16 ml of methacroyl chloride in 100 ml of hexane was addeddropwise at 0° C. After addition, the reaction mixture was stirred atthe same bath for overnight (16 hours). After filtering the white salts,the organic layer was washed with water three times (3×300 ml). Then,the washed organic layer was dried over anhydrous MgSO₄. The organicsolvent was removed by a rotary pump to give the crude title monomer(23.5 g). The monomer was purified by a flash column chromatography(purity>98%, silica gel with hexane). ¹H NMR: 6.05 (1H), 5.50 (1H), 1.95(3H), 1.65 (3H), 2.250.85 (14H).

Example 7 Synthesis of pinanyl methacrylate

Materials used:

Amount Charged Moles Source cis-Pinan-2-ol 15.43 g 0.10 Fluka Et₃N 12.14g 0.12 Aldrich, distilled before use Methacryloyl chloride 13.07 g 0.125Aldrich, distilled before use CH₂Cl₂ 230 mL Aldrich, dried and distilledProcedure:

All reaction glassware and needles were dried and flushed with dry N₂before use and the reaction was carried out under nitrogen atmosphere.

-   1) Into a 500 mL 3-neck round-bottom-flask equipped with an addition    funnel and a magnetic stirrer were added 15.43 g of cis-pinan-2-ol    and 200 mL of dry CH₂Cl₂ (Stirred over CaH₂ overnight, then    distilled and stored over activated molecular sieves). The    resulting-colorless solution was cooled with an ice-water bath-   2) Triethylamine (12.14 g) was added through the addition funnel to    the cooled CH₂Cl₂ solution over 10 min. After added, the resulting    solution was kept in a dry-ice/acetone bath (−67° C.).-   3) A CH₂Cl₂ (30 mL) solution of methacryloyl chloride (13.07 g) was    added dropwisely over 20 min. The resulting orangish suspension was    allowed to warm to room temperature and stirred for 2 h.-   4) The chloride salts were filtered off. The filtrate was washed    with saturated Na₂CO3 solution (2×200 mL), then DI water (3×200 mL),    and dried over anhydrous MgSO₄.-   5) The slightly yellow CH₂Cl₂ solution was concentrated on a rotary    evaporator (bath temperature kept below 35°) to yield a clear    slightly yellow liquid product. Yield=79%. The product was judged    pure by NMR.

The foregoing description of the invention is merely illustrativethereof, and it is understood that variations and modification can bemade without departing from the spirit or scope of the invention as setforth in the following claims.

1. A photoresist comprising a photoactive component and a polymercomprising a lactone moiety provided by a monomer chosen from among:


2. The photoresist composition of claim 1 wherein the polymer comprisesphotoacid-labile groups.
 3. The photoresist composition of claim 1wherein the polymer further comprises a carbon alicyclic group fused tothe polymer backbone.
 4. The photoresist composition of claim 3 whereinthe carbon alicyclic group is a polymerized norbornene group.
 5. Thephotoresist composition of claim 1 wherein the polymer comprises aheteroalicyclic group distinct from and in addition to the lactonemoiety.
 6. The photoresist composition of claim 5 wherein the additionalheteroalicyclic group comprises an oxygen ring member and/or a sulfurring member.
 7. The photoresist composition of claim 5 wherein theadditional heteroalicyclic group has a non-hydrogen ring substituent. 8.The photoresist composition of claim 1 wherein the polymer comprises apolymerized acrylate that comprises a photoacid-labile moiety.
 9. Thephotoresist composition of claim 1 wherein the polymer further comprisesanhydride units.
 10. The photoresist composition of claim 1 wherein thepolymer is a terpolymer.
 11. The photoresist composition of claim 1wherein the polymer is a tetrapolymer.
 12. The photoresist compositionof claim 1 wherein the polymer is at least substantially free ofaromatic groups.
 13. The photoresist composition of claim 1 wherein thepolymer is completely free of aromatic groups.
 14. The photoresistcomposition of claim 1 wherein the photoactive component comprises oneor more photoacid generator compounds.
 15. The photoresist compositionof claim 1 wherein the photoresist is a chemically-amplifiedpositive-acting resist.
 16. A method of forming a positive photoresistrelief image, comprising: (a) applying a coating layer of a photoresistof claim 1 on a substrate; and (b) exposing and developing thephotoresist layer to yield a relief image.
 17. The method of claim 16wherein the photoresist layer is exposed with radiation having awavelength of less than about 200 nm.
 18. An article of manufacturecomprising a microelectronic wafer substrate having coated thereon alayer of the photoresist composition of claim 1.